Field of the Invention
The invention concerns an occupant protection control system with at least two occupant protection control devices for controlling two or more occupant protection systems in a vehicle. The invention is directed in particular at an occupant protection control system including at least two airbags, but also for occupant protection systems of other types, for example rollover bar and/or belt pre-load systems.
For triggering the occupant protection system in the event of an accident, the output signals emitted by crash sensors are continuously monitored. In the event of abrupt changes of the output signals, signaling an accident, the occupant protection system, in particular an airbag, is activated. At the same time, the output signals emitted by the crash sensors are registered in a non-volatile memory, so that an accident data recorder is provided. The output signals reproduce in particular the speed profile and the decelerations of the vehicle for a certain period of time before the instant of the accident until the accident itself, but may also include further data essential for the way in which the accident happened, and consequently for its reconstruction, such as for instance the lateral acceleration of the vehicle.
If a plurality of occupant protection systems, for example a front airbag and a side airbag, are present, each of the control devices of these occupant protection systems may contain its own non-volatile memory, in which in the event of an accident the accident-related parameters measured by the control device such as speed and deceleration are stored independently. This allows a better reconstruction of the way in which the accident happened, since accident-relevant parameters measured by various control devices are then stored independently of one another and consequently additional statements concerning the events immediately before the accident are provided. However, here there arises the problem of correlating the crash recordings on a time basis during the later attempt at reconstruction, since it may not be possible to reconstruct the respective points in time of the data recordings with certainty and it is consequently problematical to assign a time to the accident-relevant data stored in the separate control devices. Furthermore, in this case each control device is provided with a non-volatile memory, which increases the outlay in terms of hardware.
Published, European Patent Application EP 0 693 404 A2 discloses an occupant protection control system having a central control device, which is equipped with a centrally disposed collision sensor and with memories (RAM, ROM, EEPROM). There are also side collision sensors, the output signals of which are subjected to a threshold value comparison. The digital comparison result data are likewise applied to the central control device, which takes the triggering decisions in dependence on the respective sensor signal states. The occupant protection control system contains driver and passenger airbags, side airbags and belt pre-load devices, which are all controlled by the central control device.
Published, European Patent Application EP 0 649 777 A1 is directed at an occupant protection control system which is equipped with a single central control device with RAM, ROM, EEPROM. The central control device receives not only acceleration sensor signals, but also further operating parameters such as ABS activation, brake and accelerator pedal actuation etc., and controls occupant protection systems such as belt pre-load devices, front and side airbags. The control device is equipped with a circulating memory, in which the acceleration sensor data and further operating parameter data, supplied on the vehicle bus, are stored for a certain time period before and after a triggering event. An accident data recorder function is consequently provided.
It is accordingly an object of the invention to provide an occupant protection control system and a method of controlling the occupant protection control system which overcome the above-mentioned disadvantages of the prior art devices and methods of this general type, which permit a novel form of storage of accident-related data facilitating accident data evaluation.
With the foregoing and other objects in view there is provided, in accordance with the invention, an occupant protection control system, including at least two occupant protection control devices for controlling at least two occupant protection devices disposed in a vehicle. One of the at least two occupant protection control devices has a control unit, a non-volatile memory for permanent storage of accident-related signals in an event of an accident, and a volatile memory. The volatile memory storing data sensed and supplied by the other of the at least two occupant control devices. In the event of the accident, the control unit initiates and controls a re-storage of the data stored in the volatile memory into the non-volatile memory.
In the case of the invention, in one control device there is further stored the data relevant for a possible accident determined by another control device. For this purpose, in addition to the non-volatile memory of the control device there is a further, volatile memory, in which the signals generated by the sensor or sensors of the other control device are stored. In the event of an accident, there takes place not only a storage of the accident-relevant data determined by the control device containing the non-volatile memory in the non-volatile memory but also a re-storage of the accident-relevant data determined by the other control device and stored in the further, volatile memory into the non-volatile memory. Since the accident-relevant data of the two control devices then stored in the non-volatile memory in each case reproduce the same time interval and consequently are correlated in time with certainty, the later reconstruction of the way in which the accident happened is unproblematical and can be performed on the basis of the multiplicity of data available (from at least two control devices) with a high degree of precision of the statements made. Furthermore, it is not necessary to equip the further control device with a non-volatile memory of its own, so that the outlay in terms of hardware required for this control device is reduced.
With the foregoing and other objects in view there is further provided, in accordance with the invention, a method of controlling an occupant protection control system having at least two occupant protection control devices, which includes:
storing accident-relevant data of a first control device in a non-volatile memory of the first control device in an event of an accident;
storing continuously data of a second control device in a volatile memory of the first control device; and
re-storing the data of the second control device stored in the volatile memory into the non-volatile memory when the accident is sensed as further accident-relevant data.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in an occupant protection control system and a method of controlling the occupant protection control system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.